Flatband voltage shifts on ther order of -2 volts/104 rad (Si) are observed for all MOS devices with 1000 R thick oxides irradiated at temperatures below 100°K. For example, the radiation hardness of "process optimized" oxides, which are radiation hard at room temperature with threshold shifts of -1V/106 rad (Si) for 1000 Å oxides, is degraded by two orders of magnitude when irradiated below 100°K. Flatband voltage shifts as small as0-1 volt per 106 rad (Si) have been measured on thin oxide MNOS capacitors irradiated at 80 K. The threshold shift in a p-buried channel CCD linear shift register, fabricated with an oxide/ nitride dual gate insulator and double-level polysilicon gates and irradiated with the device operating, was -1 volt after 10° rad (Si) dose at 80°K. The CCDs were operational using the preirradiation bias conditions after 10° rad (Si) at 80°K, and the CCD transfer efficiency was essentially unchanged at 0.9999.